Investigating Trade-offs Between Reproduction, Aging and Immunity in Monarch Butterflies
Monarch butterflies are a unique system to study the tradeoffs between reproduction aging and immunity due to their unique life history traits. One generation emerges later in the season and travels great distances to the overwintering grounds in Mexico and the Southern United States. As a result of this later emergence and great migration, there are a variety of differences between the two morphs of the same species. Here, we show that these two morphs differ in their immune responses and reproductive traits. Butterflies who lived longer had smaller testis. The timing of the immune measures (day 7 or day 21) following emergence played a role in the number of hemocytes present and the amount of hemolymph protein. We show that testis size decreases with days spent alive which could be due to relocation. Additionally, we show that there are trends in immune responses that favor the immune challenged group over the control.